Bistrians Billy Mack

Driveshaft out of phase?

18K front axle w/old style grease-lubricated wheel bearings. 23K front would have 12 lugs. 55K bogie. Should be a stamped # on the axle 'bowl' SWS 68C or SWS-681C (C if s-cam brakes; W if wedge brakes). 65K bogie would be SWS-592C(W) & would have fewer but thicker spring leaves. She's a Classic Heavyweight! 👍

If you go to your local Mack dealer, ask them if the Parts System still supplies the A/C retrofit kit for R/RD/RW models. They used to but I'm not sure if the entire 'kit' is still available. The kit encompassed the condenser assby. for mounting in front of the radiator, the compressor, compressor mounting bracket, receiver-drier w/mounting bracket, drive belt, hoses, fittings & clamps and the complete cab 'under dash' unit which was the combination A/c evaporator & heater. Being your vehicle probably has CMCAC (chassis mounted charge air cooling), the condenser would mount below the charge-air core which is in front of the radiator. I'd start with asking your local Mack Parts Department if a kit is available to retro-fit your particular truck. It won't be cheap but it beats scrounging around for used parts that may/may not be reliable. You'll have all new stuff to work with as well as the instructions included in the kit. I did a retro-fit on a '77 RD686ST a LONG time ago - it was tedious but worth the effort having a cool cab on a hot Long Island day! Hope this helps you out here! Bill

Mack used to list their chassis by specific model #'s. For example: RWS786LST was a SuperLiner, tandem axle, ENDT676 (285hp) Maxidyne engine & tractor configuration. The 'RW' at the beginning was when Mack started building the SuperLiner @ the Hayward California assembly line to replace the RL/RS 700 western models. So if you went back to the 70's before SuperLiner production started, the same truck would've been RS786LST or RL786LST if it had aluminum frame rails. Once the RS/RL 700 models were discontinued, they used the RW for the SuperLiner. The last 2 numerical digits in the model # designated the engine. Some examples: RWS753LST and RWS754LST were SuperLiner chassis with a 3406 engine RWS788LST were SuperLiner chassis with Mack 350 engines RWS767LST were SuperLiner chassis with Cummins engines And for an Allentown built 'R' model, something like an R795ST would be an R700 tandem axle chassis, tractor configuration with the ENDT-865 Maxidyne V-8 engine. Later year productions, Mack changed over to simply RW712 (single axle chassis), RW713 (tandem axle chassis). The specific vehicle specs were included in the VIN. The SuperLiner also had a lighter version (smaller frame rails, limited axle sizes, etc.) & was the RW613 model usually found in tractor applications. The RW713, having heavier frame rails & more options for heavier drive train components, were heavy-haul tractors, dump trucks, etc. Hope you're not totally confused by now but if you need any other info, don't hesitate!

You've got a classic R model there so why not stay with the original Mack colors. Mack Green or Mack Red with gloss black chassis components & grey rims as it would've come off the assembly line & would look good, especially with the new paint formulas that are available these days vs. the old ones (DuPont Dulux enamel, etc.). You could break-up the green on the hood with gloss black fenders, grille area & the brow where the bulldog sits.....there're good edges there for taping off when you do the accent. The lower edge of the hood striping would be your break point between the colors. It's just an idea but there were a lot of companies that used that combination back in the day (Yonkers Contracting, C & K Petroleum Transporters, Gulf Oil Co.). Mack used to have a paint scheme page if you were ordering a new chassis back in the late 60's & 70's & the customer could pick what he wanted. I had those pages at one time but are long gone now. Just some thoughts!

No longer available from Mack Parts?

Superliner cab is different too!

Turbo can't build up enough boost (air) at RPM's below 1500 to successfully burn the fuel being injected (black smoke/incomplete combustion). It puts a strain on the pistons & rings as well as pushing up the exhaust temps. Biggest thing is that the insufficiently burned fuel in the cylinders can score your piston liners & rings. Used to be called 'scrubbing' that will lead to blow-by, oil consumption as well as diluting the oil in your crankcase. Plus, the carbon build-up on the valves & pistons would be substantial. A real bad practice & kinda shows what the driver's skill 'isn't'!! Basically, if you like lugging the engine all the time, lay aside enough $$ to do an in-chassis rebuild down the road. The dash plate should say (at the bottom): 'Do not overspeed or lug engine'. They mean it!

Anytime!

With the '3' after the B75, it was equipped with the ENDT-673. Horsepower is 205 @ 2100 RPM. Firing order is 1-5-3-6-2-4. Normal cyl. compression is 425 - 460 PSI. 560 ft.lb. torque @ 1400 - 1600 RPM. Issues? None really other than make sure the injection pump timing is correct, keep your oil, air & fuel filters regularly serviced, your valves properly adjusted (cold static setting), keep the engine RPM's within the operating range (1500-2100) & no lugging. Mack used to have metal plates on the dash panels that told you the operating ranges of the particular engine that was in your truck. The 205 HP turbo was in existence during the late 50's & early to mid 60's & then they upped the HP to 225 and later to 250 (ENDT-673C). Sounds like a classic workhorse truck ~ a 'true survivor'! Hope it has power steering! Good luck with it! .

Check your wiring 1st (pump switch, valve covers) & then the solenoids (1 for each head on the rocker arm shaft) before you go spend a ton of $$ for a Jake Brake kit.

It should be an American Bosch APE-6BB series pump.......should be a riveted tag on the outboard side of the pump that has the model #, serial # & timing specs.

What truck, what year & what engine?

This sounds like a check valve issue......Is there an air dryer on this tractor & does it purge when the compressor unloads @ 115-120 psi? Have you checked/drained all the tanks (primary & secondary) to make sure they're not full of water from condensation? If I can find my old schematics, do you have a fax # ~ I'll send them to you. Bill

1200 to 2100 RPM